This invention relates to a valve assembly for a gas turbine engine. Specifically, this invention relates to a valve assembly that controls the amount of cooling air supplied to a nozzle a of a gas turbine engine.
The major components of a gas turbine engine include (beginning at the upstream end, or inlet) a compressor section, a burner section, a turbine section, and a nozzle section. The engine may have an afterburner section between the turbine section and the nozzle section.
If the engine is a turbofan, then the compressor section includes a fan section at the upstream end. After passing the fan section, the turbofan engine separates the air into two flow paths. A primary flow (also referred to as core engine flow) enters the remainder of the compressor section, mixes with fuel, and combusts in the burner section. The gases exit the burner section to power the turbine section.
A secondary flow (also referred to as bypass flow) avoids the remainder of the compressor section, the burner section and the turbine section. Instead, the secondary flow travels through a duct to a location downstream of the turbine section. The secondary flow mixes with the primary flow downstream of the turbine section.
As necessary, the afterburner section could augment the thrust of the engine by igniting additional fuel downstream of the turbine section. The flow then exits the engine through the nozzle.
The engine must supply cooling air to the nozzle in order to protect the nozzle components from the high temperature exhaust. Typically, the engine diverts secondary flow from the fan section to cool the nozzle section.
The greatest demand for cooling air to the nozzle occurs when the afterburner operates. As an example, the pilot operates the engine at maximum thrust (with the afterburner operating) in a conventional take-off and landing (CTOL) configuration. The CTOL configuration requires the greatest amount of cooling air to the nozzle.
Certain non-augmented operations of the engine (i.e. without the afterburner operating) also require cooling air. However, the amount of cooling air need is a reduced amount from augmented operations. As an example, a short take-off vertical landing (STOVL) configuration requires maximum non-augmented thrust from the engine. The non-augmented exhaust, while still at an elevated temperature, exhibits a lower temperature than during augmented operations. Accordingly, the engine can accept a reduced supply of cooling air to the nozzle when in the STOVL configuration.
Conventional valve assemblies have never compensated for the reduced need for cooling air in the STOVL configuration.
It is an object of the present invention to provide a new and improved valve assembly.
It is a further object of the present invention to provide a valve assembly that provides cooling air to a nozzle of a gas turbine engine.
It is a further object of the present invention to provide a valve assembly that adjusts the rate of cooling air provided to the nozzle.
It is a further object of the present invention to provide a valve assembly that adjusts the cooling air flow rate depending on engine configuration.
It is a further object of the present invention to provide a passive valve assembly.
It is a further object of the present invention to provide a valve assembly that uses a passive actuator.
It is a further object of the present invention to provide an actuator that does not require a discrete motor.
It is a further object of the present invention to provide a lightweight valve assembly.
It is a further object of the present invention to provide a valve assembly that increases the available thrust of the engine during certain configurations.
These and other objects of the present invention are achieved in one aspect by a gas turbine engine. The engine comprises: a compressor section; a burner section; a turbine section; an afterburner section; a nozzle movable between a first configuration and a second configuration; and a valve assembly for supplying cooling air to said nozzle. The valve assembly reduces the cooling air to the nozzle as the nozzle approaches the second configuration.
These and other objects of the present invention are achieved in another aspect by a nozzle for discharging exhaust from a gas turbine engine. The nozzle comprises: a first section; a second section movable relative to the first section between a first configuration and a second configuration; a plurality of flaps defining an exit for the exhaust; and a valve assembly providing cooling air to the flaps. The valve assembly reduces the cooling air to the flaps as the nozzle approaches the second configuration.
These and other objects of the present invention are achieved in another aspect by a valve assembly for a nozzle of a gas turbine engine. The valve assembly includes: a first member having openings that receive cooling air; a second member placed adjacent the first member and having openings that receive the cooling air from the first member; and an actuator for moving the first member from a first position, which allows a first flow rate of cooling air to pass through the openings, to a second position, which allows a second flow rate of cooling air to pass through the openings. The second flow rate is less than the first flow rate.